The obstructive sleep apnea syndrome (OSAS) is a common cause of morbidity in childhood. Arousal from sleep during airway obstruction has been regarded as a protective reflex that reestablishes airway patency and prevents severe, life-threatening asphyxia. Termination of an obstructive apnea by arousal has been clearly shown in adults. Children, in contrast, often do not have cortical arousals in association with apneas. It is unclear whether this lack of arousal in children is due to a general defect in arousal mechanisms, or to more specific defects. We have previously shown that children with OSAS have blunted arousal responses to respiratory stimuli, such as hypercapnia and increased inspiratory resistance. However, it is not known whether these arousal deficits to respiratory stimuli are due to blunting of the arousal response secondary to chronic nocturnal hypercapnia and upper airway obstruction, or whether they are due to an intrinsic abnormality in the arousal response. We hypothesized that children with OSAS have a generalized deficit of arousal mechanisms. The objective of this study is to analyze whether the overall arousal threshold is abnormal, by evaluating the arousal response to a non-respiratory (acoustic) stimulus. In this study, children with OSAS and age-matched controls will undergo a nocturnal sleep study during which electrocortical arousal to a graded acoustic stimulus will be evaluated. These experiments will help elucidate the underlying pathophysiology of childhood OSAS, resulting ultimately in improved management of this disease.